FIG. 1 shows a vacuum cleaner 10 according to the prior art. The illustrated vacuum cleaner 10 has a handle 12, a nozzle 14 and a dirt receiving receptacle 16. A dirty air conduit 18 connects the nozzle 14 to the dirt receiving receptacle 16. The nozzle 14 has a front portion 20 and a rear portion 22. A resilient bumper 24 surrounds the nozzle 14 to protect walls and furniture from damage. Other types of vacuum cleaners can be equipped with separate nozzles 14 that can be powered or un-powered.
The vacuum cleaner 10 removes dirt from a carpet by creating a suction under the nozzle 14 of the vacuum cleaner 10 that is strong enough to draw the dirt particles from a section of the floor into the vacuum cleaner 10. The dirty air travels from the nozzle 14, through the dirty air conduit 18, and into the dirt receiving receptacle 16 where the entrained dirt is captured.
FIG. 2 shows the nozzle 14 of the prior art from below. A fan (not shown) draws dirty air from the carpet or floor into the vacuum cleaner 10 through an opening 26 in the nozzle 14. To increase the efficiency of this process, the opening 26 in the nozzle 14 of the vacuum cleaner 10 often has a roller brush 28 for agitating dirt from the carpet as it is being vacuumed.
The underside of the nozzle 14 is covered with a bottom panel 30. The bottom panel 30 has a lowered section 32 corresponding to the front portion 20 of the nozzle 14, and an elevated section 34 corresponding to the rear portion 22 of the nozzle 14. The lowered section 32 encircles the opening 26, and extends roughly one-half inch below the elevated section 34, as defined when the nozzle 14 is in the position of use. When the vacuum cleaner 10 is in this position, the lowered section 32 contacts the floor.
Two support wheels 36 extend through the elevated section 34 of the bottom panel 30 toward the rear portion 22 of the nozzle 14. Each support wheel 36 is approximately one and one-half inch in diameter and one inch wide and extends approximately one-half inch below the surface of the bottom panel 30, countering the tilting effect that the lowered section 32 has on the nozzle 14, and causing the nozzle 14 to sit level. Both of the support wheels 36 are large enough to raise the nozzle 14 above the floor whether the vacuum cleaner 10 is operating on a hard surface or carpet.
Generally, when the vacuum cleaner 10 is operating, the decreased pressure under the nozzle 14 caused by the evacuation of air into the opening 26 causes the surrounding air to flow under the nozzle 14. The smaller the gap between the nozzle 14 and the floor, the higher the velocity of the air rushing under the nozzle 14. One upright vacuum in particular, the ORECK Model XL9100HG, utilizes a pair of channels 38 to concentrate this rushing air from the sides of the nozzle 14. This concentrated suction can draw dirt particles from the base of a wall or a base board under the nozzle 14 and direct the dirt-entrained air into the opening 26. A similar design is disclosed in U.S. Pat. No. 4,219,902 to DeMaagd. To aid in releasing dirt particles from the bottom of walls or base boards, angled bristles 44 are mounted to the lowered section 32 of the bottom panel 30. The angled bristles 44 are directed downward and to the side, toward the intersection of a wall (not shown) with a floor 46 (FIG. 4).
As shown in FIG. 3, the portion of the lowered section 32 that extends along the bottom of the front portion 20 of the nozzle 14 is made up of alternating teeth 40 and gaps 42. This structure creates increased air flow velocity into the opening 26 from the front of the vacuum cleaner 10.
One problem with this design is that the angled bristles 44 eventually become distorted beyond the point of elasticity and can no longer serve their intended purpose. When the nozzle 14 is in the position of use, as shown in FIG. 4, the lowered portion 32 of the bottom panel 30 of the nozzle 14 sits flat on the floor 46. This causes the angled bristles 44 to be flared into a horizontal orientation. Whether the nozzle 14 is being used or stored in this position, the angled bristles 44 are held in this position. Eventually, the angled bristles 44 permanently retain this position, and no longer exert any downward force against the floor. If the angled bristles 44 become so distorted that they begin to turn upward, the angled bristles 44 no longer effectively remove dirt from the corner.
Another problem with this design is that the lowered section 32 of the bottom panel 30 contacts the floor. The edges and corners of the lowered section 32 can scratch linoleum and hardwood floors. As the angled bristles 44 lose their resilience, the force that these edges and corners exert on the floor can increase and cause even greater damage. Even worse, the portions of the nozzle 14 that contact the floor can become embedded with glass or other sharp materials which can seriously damage a floor.
A need therefore exists for an improved brush and spacer assembly for upright vacuum cleaners.